Apparatus for producing glass fibers



July 11, 1950 E- J. cooK APPARATUS FOR PRODUCING GLASS FIBERS 3 Sheets-Sheet 1 Filed Dec. 11, 1945 K s M r O E C v m EI 0 WW I M m a E B Jul 11, 1950 Filed Dec. 11, 1945 E. J. cooK 2,514,627

APPARATUS FOR PRODUCING GLASS FIBERS 3 Sheets-Sheet 2 I me 53 52 Q I |4- Q 52 42' 40 w) J g \7": I u 59 59 5 58 43a 7 1 I 98 97 9e 75:

.90 l IO 91\/ E I l as? I 7////{ lo 1 A ETT mos'kron EVER .rc 96 4-00 101 gr July 11, 1950 E, J. COOK 2,514,627

APPARATUS FOR PRODUCING GLASS FIBERS Filed Dec. 1.1, 1945 3 Sheets-Sheet 3 INVENTOR EVERETTJTCOOK,

M H ATTORNEYS Patented July 11, 1950 APPARATUS FOR PRO FIBER UCING GLASS Everett J'..-Co0lr,. Toledo, Ohio, assignor, by mesne assignments; to: Glass Fibers, Inca, Water-ville,

Qhio,

Application December 11, I945, Serial No. 634,285

2 Claims 1:

This invention relates to an apparatus for pro:- ducing glass fibers, and" specifically.- to apparatus for spinning or twisting the glass fibersinto a thread or yarn immediately following the: drawing of the glass fibers.

An: object of the invention is to provide. an

apparatus wherein glas fibers or filaments? are continuously drawn and immediately upon" cooling or solidification thereof'the fibersare: twisted or spun into a thread, the drawing ofthe' glass fibers and" the subsequent spinning of '1 the thread being accomplished in a continuous operation so that the finished thread can be wound directly upon a reelor spool. Another object. of the invention is to provide an apparatus wherein fibers or filaments are drawn mechanically from: a molten or semi-solid substance, and wherein the fibers or filaments are drawn in independent groups 50 that each group of fibers be spun into a small" thread separately, which threads are subsequently brought together for spinning into a heavier thread'i Still another object of the-invention. is to provide an apparatus wherein there is provided a pluralityof individual heating crucibles or fur-- naces for heating glass and from each of which a group of glass fibers is mechanically drawn, and wherein the furnaces, or crucibles, are adapted to be rotated upon their own axes for the purpose of spinning the fibers as draw-atherofi om' into thread, and also which furnaces are adapted to-be rotated in a planetary arrangement around a central axis so thatthe threads spunby the individual furnace'mechani'sms will be further spun intoacomposit thread" for cel lecting upon a reel 01" spool.

Still another object of the invention is taprov-ide an apparatus for spinning threads from glass fibers as a continuous process during the'drawing' of the fibers wherein the type ofthread produced can be changed by varying the spinning operation.

Still another object of the invention-isto provide an apparatus for Spinning threads from glass fibers wherein the manufacture of the threadcan-be'carried forward as" a continuous process and without interruption to give arr-indeterminate length of thread.

Stillanetherobject of the invention is taprovide an apparatus for spinning threads from glass fibers wherein the controlled conditions under which the glassfibers are drawn can be changedto iegulatethe size of the drawn" fibers andthereby-regulate the size and strength-- of the thread produced therefrom.

Still: another object-of the invention is to provide: an. apparatus: whereinta pressure differential is: established on abody of molten glass and the temperature of the molten. glass as well as the rate atwhich the fibers are: mechanically drawn is maintained relatively constant after these conditions 'are'correlated toobtai'n: a, predetermined size filament, and thereafter immediately spin or. twist the fibersinto a; finished thread product.

Another object of the invention is to provide an apparatus for" accomplishing any of the fore going obj'ectiveswherein glass stock is fed into the heating crucible in response to the volume on molten; glass" therein to maintain a substan tially constant: volume of glass available from which. theg-lass fibers canbe drawn.

Further objects and" advantages will become apparent from the 'd-rawings and the following description. i

In therdrawings Figure lis' a side 'elevational view of an apparatus for drawing and" spinning glass fibersa' Figurez 'is a vert'ical'cross-secti'onal view, some what diagrammatic in -form, of the machine il liistrated in Figure-1 showing the principal constr-uctional features of the machine.

l i'guret is a vertical cross-sectional view "of one of'the feeding mechanismsfor feeding-the glass stock int'o the heating chambers of the machine.

Figure 4 is a plan' View, somewhatdiagrammati'c' in form; of the apparatus illustratedjin Figural.

Figure 5 is' a schematic wiring diagram of a power source'and electrical mechanism for operating the apparatus illustrated herein;

In this invention theglass fibers or filaments are d-ra'wn mechanically from a supply or body of molten glass in such a manner that the diameteroffthefilamentsis accurately controlled by thedrawing operation. As soon as the drawn fibers have cooled sufiflciently that there is, no further drawing thereof, they are brought. together'andspun into a thread, string or yarn, as a continuing operation ofthe drawing process. Theispun. thread, string or yarn is. then wound upon a spool or reel; a

The term :fiber or filament asusedinthisapplioatiorn refers to fibers that are. of adiameter on the order on .000325! and-variations therefrom such: as from .0001 to .0004".

There :is a=peculiar quality in glass in the man ufacturen' of glassifibers; or; filaments, in. that the tensile strength of: the glassfibersfis-increased as filaments are mechanically drawn under con-' trolled conditions under which the. lowest possible temperature of the glass consistent with good.

controlled at any predetermined value. The winding of the finished thread product upon the reel or spool 22 provides the source of power or energy required to mechanically draw the fibers or filaments from the furnaces III in a manner hereinafter more specifically described. Thus, the speed of rotation of the winding spool 22 will regulate the speed of drawing of the glass fibers Y 'or filaments and becomes one of the factors entering into the control of the diameter of the filaments.

drawing qualities, is used. Preferably, the body of glass is heated within a metal furnace by conduction and radiation from the walls' thereof} which walls are heated inductively by the use of high frequency energy. The temperature of the furnace is accurately controlled to maintain a predetermined condition of fluidity of the molten glass in the furnace so that a predetermined pressure differential applied upon-the body of molten glass will cause the molten glass to exude through a plurality of orifices in one wall of the furnace at a predetermined rate and thereby allow fibers or filaments to be drawn from globule-like reservoirs established at the outlet of each of the orifices at a predetermined rate to establish a predetermined size filament.

By controlling the temperature of the furnace,

and thus the fluidity of the molten glass therein,

the pressure differential upon the molten body of glass, the size of the orifices in the wall of the furnace and the rate at which the fibers are drawn,- the diameter of the drawn filaments can be controlled and varied tomeet any requirement.

After the fibers or filaments have been drawn a sufiicient distance from the furnace, they have cooled sufficiently to allow them to be brought together and spun into a thread. The groups of filaments that are drawn from each of the furnaces of the apparatus described herein'are first brought together to form a primary thread. This operation is produced by causing rotation of the individual furnaces and through a spinning of the filaments issuing. therefrom. Theprimary threads spun from eachof the furnaces are then brought together so that a rotation of the furnaces in a planetary arrangement around a cominon axis will cause a second spinning of the primary threads into a major thread or finished product.

The apparatus of this invention for drawing and spinning glass fibers consists of a plurality Each of the furnaces I0 consists of a crucible 39'that contains a body of molten glass 3|. The crucible 39 is constructed of a metal, preferably of a non-oxidizable nature, at the high temperatures at which the metal is worked, which in this invention will be from 2200 F. to 2300 F. Such a metal is found in platinum or in platinum rhodium alloys. The crucible 39 is provided with an aperture plate 32 that forms the bottom wall thereof. The operture plate has a plurality of aperture 33 therein, which apertures are formed in protrusions 34 that extend downward from the aperture plate 32. The molten glass within the crucible 39 exudes from the apertures 33 under controlled-conditions, hereinafter referred to and forms globule-like reservoirs of molten glass at the discharge end of each of the apertures 33. The glass filaments or fibers 35 have their genesis in the globules and are drawn therefrom by the mechanical means consisting of the spool or reel 22 hereinbefore referred to.

The crucible 30 is of relatively small size and has a high frequency coil 36 positioned around the same. The coil 36 is preferably constructed from a small patinum tube to avoid deterioration of the same at the high temperature involved in its use adjacent the crucible 39. The high frequency coil is adapted to be connected to the output of a high frequency generator or oscillating unit, such as the simplified form of such unit illustrated in Figure 5, hereinafter more fully described, for impressing a frequency frame I5 of the machine that includes the base portion. I6 thereof.

The rotatable frame H is driven by the shaft I2 which in turn carries a gear I1 engaged by the worm I8 carried upon the shaft I9. The shaft I9 is in turn driven by the electric motor 20, preferably of the variable speed type, through means of a pair of beveled gears 2|. Thus, whenever the motor 2 9 is operating,'the frame I I will rotate the furnaces I 0 in 'a planetary arrangement about the axis of the shaft I2.

The base portion I6, of the machine supports a receiving reel or spool 22 upon suitable-bearings 23. The receiving spool, which receives the finished thread product, is driven by means of an electric motor 24 that drives the same through a variable speed mechanism 25 wherebythe speed of 1.5 megacycles on the coil 36, which frequency has been found most favorable for heating the platinum crucible 30. The crucible 30 is secured upon the end-of a ceramic tube 31 that has an opening 38 therein through which the glass stock is fed into the crucible 39.

The ceramic tube 3! is carried within the upper metal body 39 of the furnace I9 and is adapted to rotate therein. The upper end of the ceramic tube 31 carries a :gear 40 secured thereto, which gear 49 may also suspend the ceramic tube 31 within the body 39 of the furnace. I

. Each of the furnaces I0 is provided with a gear 49 that meshes with a, ring gear '4I carried upon the upper face of the frame II and held in position by means of suitable guide gears 42, carried upon the pinion shafts 43a and spaced substantially equidistantly about the ring gear 4|.

The ring gear 4I rotates the inmates I9 within the body portion 39 thereof for the purpose of spinning the filaments issuing from the aperture plates 32. The ring gear 4| is driven by means of pinion gear 43 carried upon the shaft 44 secured to the frame II. The shaft 44 also carries a bevel gear 45 that engages a companion bevel gear 46 carried upon the shaft 41. A friction plate 48 is caried upon the opposite end of the shaft 41 and is spring pressed against the beveled drive member 49 by means of a spring 59. The beveled drive member 49 is keyed to be slidable upon the drive shaft I9 to allow the fork 5| tmmove the same. over: the-face! oat. the: plate; 48. and thusachangethespeediatawhiclrthe gear 4| is driven to change the speectozhaxial rotation of'the: furnaces; lllr. andthuscthe;speedat spinning. the;- filamentsis issnirg's therefrom. to; either wind: the: same tighter: or? more loosely; depend.- ing; upon' the: nature: of: the; thread desired:

The: body" member. 39.? oi: the furnace: i, supports: ahopper 52 adapted to; receive the; glass bails orr marbles: 53:: that; areaied into the; heating crucible; 3B: throixghlthe opening: 38: in. the ce" ramicitube. 31C The glassaballs 535 are. fEda'. into thecrucibletfl: oneiatatimezbwmeans ofi amelectric solenoid;= :4 actuating: a gate 55' that: is: normallyheld in; closed by: means of a spring 5.6m. Ther'operationrofl the fee'dingimecheanism; will. be. more: clearly set". forthv the description of? the; electric: circuit disclosed in*"5.'ig'- ure.

The? ceramic: tube; 3ft has an: annular recess: 55 therein that: conm'runi'cates: through an. opening 5:1 with. a2 passage: 33%.. The recess 5E also;-v com:- municateswith a aseous: pressure line- 58: that extends from an: anmilanrecess 5L in the upper faceiot. the? rotating frame H this latter recess: 59 communicating with a. gaseouszpressure; line? 26 connected to: a suitables source: of: gaseous pres"- sure; whereby: gas: under: pressure: is: supplied; to and maintained"; in thezacrucibleeiitll: to slowly: exude the moltenuglassthrough theaperturessiii-i in: the

aperture plate: 3'2. sealing ring 2LT is carried upon the stationary'head l -3a andengagesqt'her m.- tating' framee H; to: seal! the joint therebetween and 'preventloss of gaseous pressure. The dousble: gate.v arrangement. consisting." of the gate 55 and the gate 55a; in the feeding: device prevents loss of pressure" from the; crucible 32% when a ball is: beingafe'ct thereintoi The gaseousipressure supplied to; the-. crucible 3031s: suitably controlled by any conventional well? known means: to. maintain 4 is in. effect a mercury thermometer having: the

threeeiterminalsiil'; 92 and 93" passihgrthereinto into: engagement: with the' m'ercuryr column 94:.

Thor terminal: 93 is: at common terminal or ground connection. The upper terminal: SL controls theoutput of the? oscillator in a manner i hereinafter described to maintain the temperature: of" the" crucible 30 substantially constant. Theterminal; 92* also controls the oscillator and is adapted to: out in a. stand-by tube irr case the temperature of the" crucible 30 should. drop below a predetermined" value for some accidental or unusual reason.

The" electrical system for controlling. the tem-.- perature of the crucible 30; and for controlling the feeding? of the glass balls% 53 is more-particw larly illustrated: in: Figure 51 wherein there is shown a simplified form: 0t highv frequency os' cillat'om.

In the: electrical Wiring diagram shown in Fi ure 5-, thereis illustrated a fullwave rectifierfii) having. the-output terminals: 6t and 62 thereoil- An oscillator or high frequency genera-tor T6 is connected to! the: output; terminals 5-11 and of the; rectifier; 59 The: high frequency genera-tor may consist of a conventional.oscillating circuit 6 to obtain thedesired. frequency on the. output side. thereof" for delivery to. the: high frequency coil-{36; Asjillustratedin Figure.- 5-, the; high ire-- quency generator may consist of. anoscillator tu'be 'H- and astand-by; oscillator. tube 1.2 that issupplied with current, from the rectifier 60 Onesidev of the.;transfor-mer i3: is connected to the. anode. 14 of theoscillator" tubes H and 112, andthe'other side of the transformer'laiscon.- nected-with the cathodes l5oftheoscillator tubes H and-. 1 2 in convention-ah manner' inf cooperation with the. rectifier so. The: secondary coil; Hi.- of the transformer 13-: has the: opposite; terminals thereof connected with. the opposite terminals oi the high frequency coil; 3&- for thereby; transmitting the energy( of the high: frequency generator tathe-high frequoncyrcoil. The-gridz-exciting coil 7:1,.that maybe-a compound winding in the trans?- former l3; suppliesvthe grid circuit of.- the-oscillator tubes. 'H- and; 'i-2--, byvarying, thevoltage in the-grid circuit at the-oscillator tubes-1ft and l2, the-output; 0t. theso seillaton MLv isthereby controlled. Su.ch-:a:contrc-l of: thezgrid circuit may. be had through the potentiometer 118- The. grid: circuit ofthe. oscillator tube.- Lk is continuously in circuit: while; the. grid circu-itoi. the oscillator tube-12r provided with.- the con.- tacts Bel? that are operated by the relay; coil B that is placed in. circuit. with the term-inalz: 9.2: at thetemperature-sensitiua device Ellis. The contacts Bi, are opened; when; the relay B is energized, W-hichds .a .noizmal condition; thereby allowingthe. tube. i lto.,.act-:asza standeby. tube;

The potentiometer 18 ctthe high: frequency generator It isiadapteditoifloat ouer-therresistance element thereof: to: control; the output off the gen.- erator, as this. potentiometer isycausedc to operate by the electric. motor. 8.0 The electricmotor 8! is adapted: toocause the.- potentiometer to move one. direction: and: a torsion: spring 8;! connected totheshaft. between. the motor 89' and the potentiometer 18 is adaptedg to. cause the potentiometer tormove, amopposite: direction:v lihe direction 0t movement, of: the; potentiometer.- to Vary its resistance. is. cont-rolled.- by. the position oi the mercurycolumn; 94- in. the temperature sensitive device: 99 with; relation. to the terminal 91. thereof... When, the. mercury. columimfii engages the; terminal. 9A or. israbove the. same, an electric. circuit, willbe made through: relay coil A whichclosesr'thecontacts Al. and thereby energizes; the. motor 8.9.: to actuate. the potentiometer 1:3 and reduce the. output of; the high frequency generator Conversely, when the mercury; column 554, is. below.- the. upper terminal 3.1, oil the, temperatureesensi'tive.device. 98, the. re lay coil A will be Lie-energized, thereby; de-energizing, the. electric. motor and. allowing; the torsion. spring, 8 I. tdactuate the. potentiometer 13 in theopposite. directiomand-thereby increase the output of: the. high. frequencyr generator. 10... It will thus be. seen that the.temperature-sensitive device: Sill will thuscontrohtheo-utputsof, the high frequency generator 1.0 with suificiently'close, ac..-

- curacy as. to. maintain the. temperature of the crucible 3.0,ata substantially:constantvalue. The preferable temperatuueconditions int-clued; are approximately 2250? plusror minus- 110, E.

As previously: mentioned. the oscillator tube i2- actsas .astand-by tube, and: assuming the ap. paratus; is in; operation, them-erasur column 34 of the temperature-sensitive, device at will. be above. the terminal; 93; thereoi. thus: maintaining energized the relay coil 13.. thinous-h the: holding circuit contacts B2. that. are. closed, thus holding the'contacts"B1 open to render the grid'circuit of the tube I2 ineffective. Should the temperature of the crucible 36 fall sufiiciently low that the mercury column of the temperature-sensitive element 90 disconnects with the terminal 93, the relay' coil B will be deenergized, thus allowing contacts B1 to close to cut in the second oscillator tube 12 andthus quickly and substantially increase the output of the high frequency generator H! to overcome the abnormal condition.

The solenoid 54 for feeding the glass marbles 53 in the crucible 30 is normally inactive as long as the molten glass engages the bottomend of the contact rod 95 that is connected to a contact ring 96 engaged by a contact pin 97 for conducting current thereto through the line 98, the spring 56a holding the gates 55 and 55a in the position illustrated in Figure 3. The contact switch 95:: representing the end of the contact rod 95 will'retain the relay coil D energized as long as the volume of glass is sufiiciently high to hold the contacts DI open thus retaining the solenoid 54 de-energized. When the level of the glass falls below the bottom end of the contact rod 95, the

I relay D will be de-energized, thus allowing the contacts DI to close de-energizing the solenoid 54, thus causing the gates 55 and 55a to move in a rightward direction to allow the marble on the gate 55 todrop into the crucible 30.

A delayed action switch 96a is provided in series with the solenoid 54 which is opened when the solenoid armature reaches the extreme limit of its rightward movement, thereby de-energizing the solenoid to allow the same to return to its previous position. However, the delayed action switch 96a is arranged so that the glass marble 53"wil1 have fallen into the molten glass in crucible 30 before the solenoid reaches its initial starting position to prevent a reactuation of the 1 solenoid if the'one glass ball is sufiicient to raise the volume of the glass to a point to engage the bottom end of the contact rod 95.

If the level of the glass is sufficiently high to engage the bottom of the contact rod 95, the relay D will be re-energized to open contacts DI and thereby prevent any further actuation of the solenoid 54. However, if the single ball 53 is insufiicient to raise the level of the molten glass to the end of the contact rod 95, closing of the delayed action switch 96a will again energize the solenoid 54 because at this time the relay D will be de-energized and the contacts DI will be closed. It will thus be seen that the feeding device is capable of feeding a single glass ball upon each operation thereof and sensing the level of the molten glass before feeding another glass ball.

The delayed action switch 96a may be any conventional type but as shown in the drawing,

the delayed action device consists of a piston I99 operating within a closed chamber IOI that has a port I02 therein closed by a flapper valve I93 having a leak port IIM therein. The flapper electrical members on the furnaces Ill may be carried through the center shaft I2 and suitably connected to a connecting ring I05, having various annularly arranged contact members thereon from which and to which various electrical connections can be made for suitably connecting the electrical elements of the system. Such slip ring arrangements are well known' in theflart and it is not deemed necessary to specifically describe the same.

There are four principal factors which govern the diameter of a fiber or filament during the drawing thereof, and which factors must be correlated to obtain a desired filament diameter, and after correlation of the factors they must remain constant thereafter during the drawing of the filament to maintain-the diameter of the fila-' ment constant. These four main factors are (1) establishing a predetermined temperature of the molten glass from which the fibers are drawn and maintaining the temperature constant thereafter, (2) establishing a pressure diiferential upon opposite sides of the body of molten glass in the furnace correlated with the-temperature of the glass to exude the molten glass through the orifices in the orifice plate at a predetermined rate and maintain the pressure difierential constant during the drawing operation, (3) establishing a rate of drawing. the fibers from the molten glass at the ends of the orifices that is correlated with the temperature of the glass to mechanically draw the fibers to a predetermined degree of fineness as established by the rate of draw and thereafter hold the rate of draw constant during the drawing operation, and (4) establishing a predetermined size orifice in the orifice plate correlated to the temperature of the molten glass in the crucible and the pressure differential established upon that body of glass to permit passage of the molten glass through the orifice at just a sufficient rate to .allow drawing of the fibers from the molten glass as it exudes through the orifice at the predetermined rate established by the mechanical drawing means and still retain a reservoir of molten glass at the orifices from which the fibers can be drawn, all of which variable features and a more complete discussion thereof is fully described and disclosed in my Patent 2,495,596 dated January 31, 1950. i

From the foregoing description, it will therefore be apparent that the apparatus of this invention is capable of drawing glass fibers or filaments of a predetermined controlled diameter in individul groups from individually controlled heating crucibles. Also, that the individual fibers or filaments can be spun or twisted into a primary thread as the fibers are drawn from the furnaces, allowing of course, sufficient time for their delivery from the furnace to permit satisfactory solidification to avoid adherence of the fibers to one another. Thereafter, the primary threads are further spun or twisted together by a planetary rotation of the furnaces about a common axis to produce the major product or thread of the desired size. Also, by controlling the variable factors referredto hereinabove, it will be appreciated that the size of the filaments drawn from the furnaces can be readily changed to thereby effect a change in the diameter of the thread being produced and the strength thereof. Again, by changing the speed of rotation of the individual furnaces as well as the speed of rotation of the primary rotating frame II, either a loosely wound or tightly wound thread can be produced.

While in this description the manufacture of glass fibers has been specifically referred to, yet it will be understood that the process is applicable to the manufacture of fibers or filaments from other substances including metals and metal alloys, without any major change from the genera arrangement of the apparatus.

While the apparatus disclosed and described herein constitutes a preferred form of the invention, yet it will be understood that the apparatus is capable of operation without departing from the spirit of the invention, with reference to the manufacture of threads from drawn filaments, and that all modifications that fall within the scope of the appended claims are intended to be included herein.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An apparatus for spinning a thread from a plurality of fine filaments that includes, a heating crucible having a plurality of apertures in one wall thereof and adapted to contain a body of molten substance, means for establishing and maintaining a controlled constant pressure differential upon opposite sides of the body of molten substance to cause the substance to exude slowly through said apertures, a first means of independently variable controllable speed of operation for mechanically drawing the molten substance from adjacent the apertures into controlled diameter fine filaments, a second independent means of independently variable controllable speed of operation rotating said crucible on its own axis concurrently with the drawing of said filaments to twist the drawn filaments to controlled tightness, and a third means of independently variable controllable speed of operation for moving a plurality of said crucibles radially around a common axis to twist the twisted filaments into a thread of controlled tightness.

at which the molten glass is located therein, means for establishing and maintaining a controlled constant pressure differential upon opposite sides of the body of molten glass to cause the same to exude slowly through said apertures in streams of at least the diameter of the apertures, a first means of independently variable controllable speed of operation for mechanically drawing and attenuating the glass from said streams into controlled diameter fine filaments,

2. An apparatus for spinning a glass thread from a plurality of fine filaments that includes,

a heating crucible having a plurality of apertures in one wall thereof of larger diameter than filaments to be produced and adapted to contain a body of molten glass, a high frequency heating coil encircling said crucible at the level thereof a second independently controllable means for rotating said crucible on its own axis concurrently with the drawing of said filaments to twist the drawn filaments to controlled tightness, means drivingly connected with said second independent means for effecting a change in the speed of rotation of said crucible and effect a change in the tightness of twisting of said filaments, a third independently controllable means for moving a plurality of said crucibles radially around a common axis to twist said twisted filaments into a thread of controlled tightness, and means drivingly connected with said third independent means for effecting a change in the speed of movement of said plurality of crucibles about said common axis and effect a change in the tightness of twisting of the thread.

EVERETT J. COOK.

REFERENCES CITED The following references are of record in th file of this patent:

UNITED STATES PATENTS Number Name Date 702,163 Strehlenert June 10, 1902 2,187,094 Pink Jan. 16, 1940 2,229,489 Barnard Jan. 21, 1941 2,234,986 Slayter et a1 Mar. 18, 1941 2,294,266 Barnard Aug. 25, 1942 2,369,506 Weibel Feb. 13, 1945 

1. AN APPARATUS FOR SPINNING A THREAD FROM A PLURALITY OF FINE FILAMENTS THAT INCLUDES, A HEATING CRUCIBLE HAVING A PLURALITY OF APERTURES IN ONE WALL THEREOF AND ADAPTED TO CONTAIN A BODY OF MOLTEN SUBSTANCE, MEANS FOR ESTABLISHING AND MAINTAINING A CONTROLLED CONSTANT PRESSURE DIFFERENTIAL UPON OPPOSITE SIDES OF THE BODY OF MOLTEN SUBSTANCE TO CAUSE THE SUBSTANCE TO EXUDE SLOWLY THROUGH SAID APERTURES, A FIRST MEANS OF INDEPENDENTLY VARIABLE CONTROLLABLE SPEED OF OPERATION FOR MECHANICALLY DRAWING THE MOLTEN SUBSTANCE FROM ADJACENT THE APERTURES INTO CONTROLLED DIAMETER FINE FILAMENTS, A SECOND INDEPENDENT MEANS OF INDEPENDENTLY VARIABLE CONTROLLABLE SPEED OF OPERATION ROTATING SAID CRUCIBLE ON ITS OWN AXIS CONCURRENTLY WITH THE DRAWING OF SAID FILAMENTS TO TWIST THE DRAWN FILAMENTS TO CONTROLLED TIGHTNESS, AND A THIRD MEANS OF INDEPENDENTLY VARIABLE CONTROLLABLE SPEED OF OPERATION FOR MOVING A PLURALITY OF SAID CRUCIBLES RADIALLY AROUND A COMMON AXIS TO TWIST THE TWISTED FILAMENTS INTO A THREAD OF CONTROLLED TIGHTNESS. 